Measurement of hepatic venous pressure gradient (HVPG) is a standard method for the assessment of portal pressure and correlates with the occurrence of its complications. Liver stiffness measurement ...(LSM) has been proposed as a noninvasive technique for the prediction of the complications of cirrhosis. In this study, we evaluated the ability of LSM to predict severe portal hypertension compared with that of HVPG in 61 consecutive patients with HCV‐related chronic liver disease. A strong relationship between LSM and HVPG measurements was found in the overall population (r = 0.81, P < 0.0001). However, although the correlation was excellent for HVPG values less than 10 or 12 mm Hg (r = 0.81, P = 0.0003 and r = 0.91, P < 0.0001, respectively), linear regression analysis was not optimal for HVPG values ≥10 mm Hg (r2 = 0.35, P < 0.0001) or ≥12 mm Hg (r2 = 0.17, P = 0.02). The AUROC for the prediction of HVPG ≥10 and ≥12 mm Hg were 0.99 and 0.92, respectively and at LSM cutoff values of 13.6 kPa and 17.6 kPa, sensitivity was 97% and 94%, respectively. In patients with cirrhosis, LSM positively correlated with the presence of esophageal varices (P = 0.002), although no correlation between LSM and esophageal varices size was detected. The area under the ROC for the prediction of EV was 0.76 and at a LSM cutoff value of 17.6 kPa sensitivity was 90%. Conclusion: LSM represents a non‐invasive tool for the identification of chronic liver disease patients with clinically significant or severe portal hypertension and could be employed for screening patients to be subjected to standard investigations including upper GI endoscopy and hemodynamic studies. (HEPATOLOGY 2007;45:1290–1297.)
Chemokines binding the CXCR3 receptor have been shown to inhibit angiogenesis via the CXCR3-B isoform, but the underlying molecular mechanisms are unknown. Aim of this study was to elucidate the ...effects of CXCR3-B on activation of members of the mitogen-activated protein kinase family, and to explore the relevance of defined signaling pathways to the angiostatic effects of CXCR3-B ligands. Human embryonic kidney (HEK) 293 cells were transfected with expression vectors encoding for CXCR3-A or CXCR3-B. In cells expressing CXCR3-A, CXCL10 (IP-10) at nanomolar concentrations induced activation of ERK, Akt, and Src, as previously described in human vascular pericytes. In HEK-293 cells expressing CXCR3-B, exposure to CXCL10 in the micromolar concentration range led to activation of the p38(MAPK) pathway, as indicated by phosphorylation of p38(MAPK) itself, and of MKK3/6 and MAPKAPK-2, that lie upstream and downstream of p38(MAPK), respectively. Similar results were obtained in cells stimulated with CXCL4 (PF4), a specific ligand of CXCR3-B. In contrast, CXCL4 was unable to activate p38(MAPK) in mock-transfected HEK-293 cells. Only a modest induction of ERK or JNK was observed upon CXCR3-B activation. In human microvascular endothelial cells, which selectively express CXCR3-B, in a cell cycle-dependent fashion, CXCL10 and CXCL4 increased the enzymatic activity of p38(MAPK). Pharmacologic inhibition of p38(MAPK) by SB302580 resulted in a significant increase in DNA synthesis and in reversal of the inhibitory action of CXCL10. In conclusion, the p38(MAPK) pathway is a downstream effector of CXCR3-B implicated in the angiostatic action of this chemokine receptor.
Following liver injury, hepatic stellate cells (HSC) undergo proliferation and migrate into damaged areas in response to chemotactic factors. HSC have been shown to regulate leukocyte trafficking by ...secreting monocyte chemotactic protein‐1 (MCP‐1), a chemokine that recruits monocytes and lymphocytes. In this study, we explored whether MCP‐1 exerts biological actions on HSC. HSC were isolated from normal human livers, cultured on plastic, and studied in their myofibroblast‐like phenotype, and three different cells lines were used. Chemotaxis was measured in modified Boyden chambers. Phosphatidylinositol 3‐kinase (PI 3‐K) was assayed on phosphotyrosine immunoprecipitates. Exposure of HSC to MCP‐1 stimulated migration of HSC in a dose‐dependent fashion. Maximal stimulation was obtained with 250 ng/mL MCP‐1, which resulted in a 3‐ to 4‐fold stimulation of cell migration. Checkerboard analysis showed that the increase in cell migration was almost completely a result of chemotaxis rather than chemokinesis. In contrast, in quiescent HSC, MCP‐1 did not exert any effect on cell migration. In leukocytes, MCP‐1 activates the pertussis toxin‐sensitive CCR2 receptor. However, transcripts for CCR2 could not be shown in HSC, and pertussis toxin only modestly inhibited MCP‐1‐induced migration. Exposure of HSC to MCP‐1 was associated with an increase in cytosolic calcium concentration, PI 3‐K activity, protein tyrosine phosphorylation. Blocking calcium influx or pretreatment of HSC with the PI 3‐K inhibitor wortmannin markedly reduced cell migration. This study shows, for the first time, a potential direct profibrogenic action of MCP‐1 via HSC chemotaxis. MCP‐1–dependent signals in these cells are not transduced by CCR2 and may be mediated by alternative chemokine receptors.
A previous report described the association of chronic autoimmune hepatitis with iridocyclitis, but at that time (before 1989), anti-hepatitis C virus antibodies were not available, so diagnosis of ...uveitis resulting from hepatitis C virus infection could not be definitively excluded.3,4 We obviously are aware that uveitis and autoimmune hepatitis are not so frequently associated, at least in our country, and we also agree with Lim and associates that there are only a few reported cases of uveitis associated with either AIH or chronic active hepatitis in which hepatitis C virus infection can be excluded as a cause of hepatitis: the patient reported by Kamal and associates, the patient described by Maìz and associates, and our report.2,5,6 Moreover, in the case described by Maìz and associates, uveitis preceded the onset of AIH, as in our case report.2,6 The observation of an association between AIH and uveitis in a more pronounced number of patients (n = 7), such as is described by Lim and associates, adds an interesting issue to this field of clinical research between ophthalmologists and hepatologists. ...much effort still needs to be made to elucidate fully the pathogenetic mechanisms underlying this association and its frequency in internal medicine.
Background/Aims
: Little is known about the role of fractalkine (CX3CL1) in the liver. The aim of this study was to investigate the expression patterns of fractalkine and its receptor CX3CR1 in ...normal human liver and in conditions of injury.
Methods
: Distribution and expression of fractalkine and its receptor were investigated using immunohistochemistry, in situ hybridization, flow cytometry and reverse transcriptase–polymerase chain reaction. In vitro experiments were conducted in HepG2 cells.
Results
: Both fractalkine and CX3CR1 were up-regulated during chronic injury, in areas of portal and lobular inflammation. In severe acute hepatitis, fractalkine and CX3CR1 were expressed at high levels not only in areas of inflammation but also in regenerating epithelial cells within bile duct-like structures, which showed co-expression of fractalkine and cytokeratin-7 or CX3CR1. The human hepatocarcinoma cell line HepG2 expressed fractalkine at the gene and protein level, and HepG2-conditioned medium was chemotactic for cells overexpressing CX3CR1. Transcripts for CX3CR1 were detected in HepG2, and exposure of these cells to recombinant fractalkine induced cell migration.
Conclusions
: This study shows that the fractalkine system is up-regulated during liver damage, and suggests that fractalkine may play a role in the recruitment and adhesion of inflammatory cells and in the biology of liver epithelial cells.
Background & Aims: Proliferation and migration of hepatic stellate cells (HSCs) and expression of chemokines are involved in the pathogenesis of liver inflammation and fibrogenesis. Peroxisome ...proliferator–activated receptor (PPAR)-γ is a receptor transcription factor that controls growth and differentiation in different tissues. We explored the effects of PPAR-γ agonists on the biological actions of cultured human HSCs. Methods: HSCs were isolated from normal human liver tissue and used in their myofibroblast-like phenotype or immediately after isolation. Activation of PPAR-γ was induced with 15-deoxy-Δ12,14-prostaglandin J2 or with troglitazone. Results: PPAR-γ agonists dose-dependently inhibited HSC proliferation and chemotaxis induced by platelet-derived growth factor. This effect was independent of changes in postreceptor signaling or expression of c-fos and c-myc and was associated with inhibition of cell cycle progression beyond the G1 phase. Activation of PPAR-γ also resulted in a complete inhibition of the expression of monocyte chemotactic protein 1 at the gene and protein levels. Comparison of quiescent and culture-activated HSCs revealed a marked decrease in PPAR-γ expression in activated cells. Conclusions: Activation of PPAR-γ modulates profibrogenic and proinflammatory actions in HSCs. Reduced PPAR-γ expression may contribute to confer an activated phenotype to HSCs.
GASTROENTEROLOGY 2000;119:466-478
Thrombopoietin (TPO), a cytokine that participates in the differentiation and maturation of megakaryocytes, is produced in the liver, but only limited information is available on the biological ...response of liver-derived cells to TPO. In this study, we investigated whether HepG2 cells express c-Mpl, the receptor for TPO, and whether TPO elicits biological responses and intracellular signaling in this cell type. Specific transcripts for c-Mpl were detected in HepG2 cells by RT-PCR, and expression of the protein was demonstrated by Western blot analysis and immunofluorescence. Exposure of HepG2 cells to TPO was associated with a dose-dependent increase in cell migration and chemoinvasion through Matrigel-coated filters. A checkerboard analysis showed that the effects of TPO on cell migration were dependent on both chemotaxis and chemokinesis. Exposure of HepG2 cells to TPO resulted in the activation of different members of the MAPK family, including ERK and JNK, as assessed using phosphorylation-specific antibodies and immune complex kinase assays. TPO also activated phosphatidylinositol 3-kinase (PI3K) and the downstream kinase Akt in a time-dependent manner. Finally, activation of c-Mpl was associated with increased activation of nuclear factor-kappaB. With the use of specific inhibitors, tyrosine phosphorylation and activation of PI3K were found to be required for the induction of migration in response to TPO. We conclude that TPO exerts biological actions on cultured hepatoblastoma cells via activation of c-Mpl and its downstream signaling.
Background & Aims: Several lines of evidence indicate that aldosterone antagonists may exert direct antifibrogenic effects. The aim of this study was to evaluate the possible direct antifibrogenic ...effects of canrenone, the active metabolite of spironolactone, in activated human hepatic stellate cells.
Methods: The effects of canrenone were assessed on platelet-derived growth factor–induced mitogenic and chemotactic effects and the increased de novo synthesis of different extracellular matrix components induced by transforming growth factor-β1.
Results: Canrenone dose-dependently reduced platelet-derived growth factor–induced cell proliferation and motility. This effect was not associated with either changes in the phosphorylation of platelet-derived growth factor receptor and phospholipase C γ or in the activation of the Ras/extracellular signal-regulated kinase pathway, whereas it was accompanied by a dose-dependent inhibition of platelet-derived growth factor–induced phosphatidylinositol 3-kinase activity. In addition, canrenone inhibited the activity of the Na
+/H
+ exchanger 1 induced by platelet-derived growth factor. The effect of canrenone on Na
+/H
+ exchanger 1 activity was reproduced by phosphatidylinositol 3-kinase inhibitors, thus supporting an inhibitory action of canrenone on phosphatidylinositol 3-kinase activity. To further address this possibility, the action of canrenone was compared with that of 2 established Na
+/H
+ exchanger 1 inhibitors: ethylisopropylamiloride and cariporide. Whereas ethylisopropylamiloride was able to inhibit platelet-derived growth factor–induced phosphatidylinositol 3-kinase activity, cariporide was without any effect. Both compounds reproduced the effects of canrenone on platelet-derived growth factor–induced mitogenesis and chemotaxis. Finally, canrenone was able to reduce transforming growth factor-β1–induced de novo synthesis of procollagen type I/IV and fibronectin and thrombin-induced hepatic stellate cell contraction.
Conclusions: These results indicate that canrenone may be active as an antifibrogenic drug.
Hepatic stellate cells (HSC) and glomerular mesangial cells (MC) are tissue-specific pericytes involved in tissue repair, a process that is regulated by members of the chemokine family. In this ...study, we explored the signal transduction pathways activated by the chemokine receptor CXCR3 in vascular pericytes. In HSC, interaction of CXCR3 with its ligands resulted in increased chemotaxis and activation of the Ras/ERK cascade. Activation of CXCR3 also stimulated Src phosphorylation and kinase activity and increased the activity of phosphatidylinositol 3-kinase and its downstream pathway, Akt. The increase in ERK activity was inhibited by genistein and PP1, but not by wortmannin, indicating that Src activation is necessary for the activation of the Ras/ERK pathway by CXCR3. Inhibition of ERK activation resulted in a decreased chemotactic and mitogenic effect of CXCR3 ligands. In MC, which respond to CXCR3 ligands with increased DNA synthesis, CXCR3 activation resulted in a biphasic stimulation of ERK activation, a pattern similar to the one observed in HSC exposed to platelet-derived growth factor, indicating that this type of response is related to the stimulation of cell proliferation. These data characterize CXCR3 signaling in pericytes and clarify the relevance of downstream pathways in the modulation of different biologic responses.
Monocyte chemotactic protein (MCP)-1 is a chemoattractant and activator for circulating monocytes and T lymphocytes. We investigated MCP-1 protein and gene expression during chronic liver disease at ...different stages, using immunohistochemistry and in situ hybridization, respectively. In normal liver, a modest expression of MCP-1 was confined to few peri-sinusoidal cells and to bile duct epithelial cells. During chronic hepatitis, MCP-1 immunostaining and gene expression were evident in the inflammatory infiltrate of the portal tract. In tissue from patients with active cirrhosis, MCP-1 expression was clearly up-regulated and was present in the portal tract, in the epithelial cells of regenerating bile ducts, and in the active septa surrounding regenerating nodules. A combination of in situ hybridization for MCP-1 and immunohistochemistry showed that activated stellate cells and monocyte/macrophages contribute to MCP-1 expression in vivo together with bile duct epithelial cells. Comparison of serial sections of liver biopsies from patients with various degrees of necro-inflammatory activity showed that infiltration of the portal tracts with monocytes/macrophages is directly correlated with the expression of MCP-1. These data expand previous in vitro studies showing that secretion of MCP-1 may contribute to the formation and maintenance of the inflammatory infiltrate observed during chronic liver disease.
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